Pontiac Repair: High Idle, genuine gm parts, pontiac bonneville

Question
Hi Todd,
I have a '92 Pontiac Bonneville SE 3800 NA. I have an intermittent high idle issue. A code 22 showed up every once in a while indicating low voltage. I checked the wiring, connector and TP sensor and found that the voltage was erratic when i played with the connector. I changed the connector and the car ran fine for about a week. The high idle returned. While checking the data on the scanner i noticed that with the engine idling and the throttle closed the throttle angle would be 4%-5%. I had a spare a TPS so i changed it. The car ran fine for a couple of months but now the high idle (1000-1500 rpm) is back.
(Should the tps voltage reading change when tapped with a screw driver?- I tried that with the old one and the throttle angle would change from 0%-5%).
Could it be another faulty TPS? Could it be something else in the wiring harness not connected directly to the TPS circuit? Could it be moisture? ECM?  

Answer
Hi Tarek:

Is is still setting a 22 dtc? No the sensor should not change when you wiggle the wires of GENTRLY tap on it if it does you have a bad connection at the sensor or the sensor it's self may be bad. do not use a aftermarket sensor use genuine GM parts. What is the TPS voltage at idle it should be low like around .40 Volt. key on engine off the tp angle should read 0% if not then you could have a issue with the ecm. If you have access to a wiring diagram see what other sensor shares the input voltage to the TP sensor you could have another sensor that is bad and it's pulling down the refrence volatge to TP like MAP sesnor or an A/C pressure sensor. That is a long shot but I have seen it happen. But I think you have an issue with the sensor and or the connection.. That said if you do not have a 22 dtc and it has a fast idle only it could be that your tp is not set right and the volatge is up over .50 volts that will do it also. It could have a vacuum leak what does the IAC valve reading show at idle with the car hot?